1. Let's add a load balancer, links, and a network in docker-compose.yml:

version: '2'
services:
  web:
    build: 
    ports:
     - "5000"
    networks:
     - l1-tier
     - l2-tier
  redis:
    image: "redis:alpine"
    links:
        - web
    networks:
     - l2-tier
  lb:
    image: dockercloud/haproxy
    ports:
     - "5001:80"
    links:
     - web
    networks:
     - l1-tier
     - l2-tier
   volumes:
     - /var/run/docker.sock:/var/run/docker.sock

networks:
  l1-tier:
     driver: bridge
  l2-tier:
    driver: bridge

2. Let's run docker_service to create Docker Compose again. This will re-build new components for our compose application:

$ ansible-playbook -i localhost, docker.yml -t recipe7

3. Let's write a task to scale the web application:

- name: Scale up web service of compose application
  docker_service:
    project_src: docker_compose
    scale:
      web: 2
  tags:
    - recipe8

4. Now, verify if both web containers are serving requests:

# Lets send multiple requests
$ for i in `seq 1 10`; do curl localhost:5001; sleep 1; done
# Lets verify logs of both web service containers
$ docker logs dockercompose_web_1
$ docker logs dockercompose_web_2